Organic peroxyacids are useful as fabric bleaching agents. As such, they are often formulated in the form of either dry, granular compositions, or aqueous suspensions, either of which products can be used in combination with detergent compositions.
An agglomeration process is known for diperoxydodecanedioic acid from published European Patent application number 0 254 331 wherein a water-impermeable material is employed as the agglomeration agent. These agglomerates are made in aqueous suspension at a temperature above the melting point of the water-impermeable material but below the melting and decomposition temperatures of the peroxyacid.
However, this process suffers from the disadvantage that you must employ a significant amount of a water-impermeable material as a binder material in order to make such agglomerates. Use of a water-impermeable material in making bleaching agents is not always possible or desirable.
Amidoperoxyacids made in accordance with EP 0 349 220 have been successfully suspended in aqueous suspensions but, after short storage periods they were found to be rheologically unstable. More particularly, the amidoperoxyacid underwent a change which led to a significant, undesirable viscosity increase. Since liquid bleaching compositions must remain pourable throughput their useful life. Products which thicken to the point of no longer being readily pourable are not commercially acceptable.
Methods for suspending some peroxyacids are known from published European Patent application number 0 347 988, published European Patent application number 0 435 379, published European Patent application number 0 176 124, published European Patent application 0 160 342 and published European patent application number 0 201 958, among others. However, none of these publications teaches or suggests a method of preparing a suspension of the present amidoperoxyacids which do not undergo a significant viscosity increase upon storage.
Accordingly, there exists a need in the art for rheologically stable suspensions of amidoperoxyacids, as well as a method for making such rheologically stable suspensions without negatively affecting one or more of the other properties of the bleaching materials and without the need for significant quantities of water-impermeable materials.